Fig. 4. Leaves of ZmUBI_pro:ZmG2 transgenic plants accumulate significantly higher levels of starch and sugars than wild-type plants.

a–d Starch (a), sucrose (b), glucose (c), and fructose (d) levels measured in flag leaves at the heading stage at 7 a.m., 12 a.m., and 7 p.m. in the field experiment in Hainan, 2019. Data are mean ± SE (n = 6 biological replicates), each dot represents a biological replicate. *P < 0.05, **P < 0.01 compared with WT according to two-tailed Student’s t test. e Hierarchical cluster analysis (HCA) of 95 primary metabolites in flag leaves at the heading stage in the field experiment in Beijing, 2018. Metabolite content is presented as median-centered averages with six biological replicates each. Red and blue colors indicate high and low content, respectively.